Potassium titanate fiber, which is not a cancer-causing substance such as asbestos, has been widely used as a friction modifier, chiefly for incorporation in a vehicle brake pad. A friction material containing such potassium titanate fibers has a very favorable advantage that it causes no damage to a brake disk while exhibiting an excellent sliding property and a good braking effect.
However, the friction material containing potassium titanate fibers exhibits a low friction coefficient in a low-temperature range. In order for the friction material to accommodate increase in speed of the vehicle and reduction in size and weight of the braking device, it must excel in friction resistance, have a higher friction coefficient and can sustain this high friction coefficient over a wide temperature range from a low-temperature range to a high-temperature range.
In the effort to solve such problems, a friction material has been proposed which contains sodium hexatitanate fibers (Patent Literature 1).
However, there still remains a need for a friction modifier which can further improve wear resistance, particularly in a high-temperature range, of a friction material.    Patent Literature 1: Japanese Patent Laid-Open No. Hei 07-196817